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Orion's Giants

December 23, 2010

Orion, the hunter, puts on a brilliant prime-time show at this time of year. The constellation is in full view, low in the east, soon after the sky gets good and dark.

To find it, look for a short line of three fairly bright stars standing straight up in the east. That's Orion's Belt. The constellation's two brightest stars line up to the left and right of the belt, roughly parallel to the horizon as they rise. The star to the left is Betelgeuse, while the one on the right is Rigel.

Both stars are supergiants. Betelgeuse is an orange supergiant, while Rigel is a blue supergiant, which means that Rigel's surface is much hotter. Both stars are larger and heavier than the Sun. As a result, they "burn" their nuclear fuel at prodigious rates, so they produce tremendous amounts of energy. That makes them very bright. In fact, both are among the dozen brightest stars in the night sky.

But this flashiness carries a big price. Since Rigel and Betelgeuse consume their nuclear fuel so quickly, they'll live fairly short lives -- in the millions of years, versus billions of years for our smaller, more sedate Sun. And both stars will end their lives with titanic explosions. For a few days or weeks, each of these exploding stars will outshine all the other stars in the galaxy combined.

In the meantime, look for these and the other stars of Orion beginning in early evening, and climbing high across the south during the night.


Script by Damond Benningfield, Copyright 2004, 2010


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